As part of the manufacture of medical self-expanding stents, stents must be compressed radially and loaded into a delivery catheter. Typically the stents are compressed down using a radial compression mechanism to a precise diameter. Then with the delivery catheter secured on one side of the compression mechanism the stent is pushed through the compression mechanism into the catheter with a rod-like device.
A deficiency of this method is that the force required to translate the stent from inside the compression mechanism into the catheter can be quite high, especially with a long stent. Since the push force is concentrated primarily on the end of the stent, the stent can be easily damaged. In some cases, to prevent damage to the stent during translation into the delivery catheter or other sheath, limiting the length of stents that can be designed and marketed becomes necessary.
Another challenge with the stent loading process is holding the delivery catheter in such a way that it is aligned precisely with the radial compression mechanism, is not deformed into a non-cylindrical shape, and the ability to accommodate a range of diameters. Typically, a hinged clamp with two v-shaped grooves or precisely cut semi-circles is used to hold the catheter in place. The v-shape grooves accommodate a wide range of diameters, but have a tendency to deform the catheter into a square shape. The precisely cut semi-circles keep the product round, but must be customized for each diameter of product and small variations of catheter diameter greatly affect the holding force.
Generally, the catheter clamp is aligned relative to the radial compression mechanism with an adjustable mechanism. It is sometimes difficult to precisely adjust alignment and over time the adjustment may change. To compensate for this, catheters are often manufactured with a funnel on the tip to help guide the stent. This funnel is typically removed in a subsequent manufacturing step.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
An object of the present invention is to provide a new and improved stent loading mechanism.
Another object of the present invention is to provide a stent loading mechanism which will not damage the stent and does not limit stent dimensions.
Yet another object of the present invention is to provide a stent loading mechanism which will align a delivery catheter without deformation thereof.